Developing effective solutions for the management of pests and diseases in lettuce JUDIT ARNÓ, OSCAR ALOMAR, NÚRIA AGUSTÍ, CRISTINA CASTAÑÉ & JORDI RIUDAVETS IRTA, Ctra. Cabrils km 2, E-08348 Cabrils, Spain Lettuce crops are of great importance in the agriculture of many Mediterranean countries. They represent intensive farming systems that involve high amount of inputs. Aphids (Nasonovia ribisnigri) are common lettuce pests in the area, early in spring plantings, and require pesticide sprays. At IRTA, we have developed and promoted the use of Lobularia maritima flower strips in order to enhance Conservation Biological Control by a complex of predators (several species of hoverflies, Orius, and coccinellids). Leaf diseases (Bremia lactucae and Botrytis / Sclerotinia), and soil diseases (Pythium, Botrytis / Sclerotinia) are also common and conventional control is based on fungicide applications. The OBJECTIVE of our demo field trial was to compare the performance of EUCLID developed solutions to control common lettuce diseases during spring with the management strategies commonly used by farmers. Our biocontrol approach with flower strips was incorporated into the EUCLID strategy. Experiments were carried out at IRTA’s Cabrils Research Center (Catalonia, Spain). In 2018, 6800 lettuces (var. Broadway; a Reddish Batavia variety) and in 2019: 6500 romaine lettuces (var. Francesca) were transplanted according to the standards of the area. All products used in the conventional strategy, are commonly used in the area, and were recommended by grower’s Pest Control Advisors. Greenhouse view (2019) This project has received funding from the European Union's Horizon 2020 research and innovation programme. Grant agreement no 633999. RESULTS: aphid control RESULTS: diseases 2018. The Incidence of leaf and soil diseases was low in both strategies, but was lower in EUCLID. MATERIALS AND METHODS Field visits were attended by farmers and technicians, that were interested in the alternatives, and valued the experience as very useful. 2019. The incidence of leaf and soil diseases was slightly lower in the EUCLID strategy, but at harvest (7th may), the incidence for both types of diseases was very similar, and did not represent a major loss. • The biological solution based on flower strips offers a successful alternative for aphid control. If climatology is not favorable for the development of natural populations of aphid predators early in the season, a strategy of releasing comercially produced predators could be implemented. • In regards to diseases, the low incidence observed does not allow to make a full economic analysis of the benefits obtained by the EUCLID strategy. • Stakeholders who participated in the demonstration days were interested in the EUCLID tools and questioned us about the outlook for registration / distribution of the products in Spain. CONCLUSIONS Trial Pest / Disease Conventional EUCLID Aphids ( N. ribisnigri ) Lobularia maritima flower strip Bremia lactucae (downy mildiu) on leaves MACH1 Pythium, Botrytis / Sclerotinia on soil ANT's Compost (before planting) Aphids ( N. ribisnigri ) Lobularia maritima flower strip Bremia lactucae (downy mildiu) on leaves ANT-Ca (formerly Califol) Pythium, Botrytis / Sclerotinia on soil ANT's Compost (before planting) 2018 2019 pesticides as advised by grower's Pest Control Advisers 2018. As observed in other previous trials, at harvest, the biological solution was as effective as the two chemical treatments applied ( ). In the absence of a pesticide sprays, aphid infestations in the EUCLID strategy were higher but were quickly reduced due to the abundant ladybirds and hoverflies in the field that were enhanced by the Lobularia flower strip. 2019. This year, the control of aphids has been less effective than in 2018 in both strategies. In spite of the four insecticide applications in the conventional plots, the development of aphid populations was very similar in both strategies. Predators were less abundant than in 2018, which may explain the lower control in the EUCLID strategy. Pest Control Advisors also reported a low efficacy of Conservation Biological Control for aphids on early lettuce crops, presumably related to the colder weather conditions this year. Conventional Euclid Bremia lactucae 25% (n= 20; very mild) 0% soil diseases 4% 3.3%